<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .bg {
            margin: 60px;
            width: 32%;
            height: 48vh;
            background: linear-gradient(-45deg, #dae, #f66, #3c9, #09f, #66f);
            background-size: 200% 200%;
            animation: gradient 8s ease infinite;
        }

        @keyframes gradient {
            0% {
                background-position: 0 12%;
            }

            50% {
                background-position: 100% 100%;
            }

            100% {
                background-position: 0 12%;
            }
        }
    </style>
</head>

<body>
    <div class="bg"></div>
</body>

</html>